Mahboobeh mohammad Yusefi Bohluli Ahmadi; Abdolreza Safari; َAnahita Shahbazi
Abstract
Abstract
Global gravity field is commonlymodelled in spherical harmonic basis functions to a certain degreeof spectral and spatial resolution. Non-uniformdistribution and different quality data limitthese functions in local gravity field modeling.Spherical harmonic basis functionsshow more global properties ...
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Abstract
Global gravity field is commonlymodelled in spherical harmonic basis functions to a certain degreeof spectral and spatial resolution. Non-uniformdistribution and different quality data limitthese functions in local gravity field modeling.Spherical harmonic basis functionsshow more global properties that means they are suitable forshowing low frequency gravityfield. In local-scale studies, radial basis functionson the sphere with quasi-local support can improve gravityfields up to a high spatial/spectral resolution.The local modelsare usually moreaccurate than global modelsin the desired locations.These functions are usually notorthogonal on a sphere, which makes the modelling process morecomplex.In this study we evaluated the radial basis functions: point-mass kernel, radial multipoles, Poisson and Poisson wavelet ,and then we compared their performances in regional gravity fieldmodelling on the sphere using real gravity acceleration data in Farscoastal area. A least-squares technique has been used toestimate the gravity field parameters. Iterative Levenberg-Marquardtalgorithm is appliedfor nonlinear inverse problem solving and minimization of differences between calculated andobserved values. These parameters include number, location, depth and scalingcoefficients in radial basis function.In order to increase efficiency Levenberg-Marquardt algorithm for solving gravity field modeling, the initial valueof theregularization parameter determined with a relation based on objective functionJacobian and also a method is provided for this parameter updates. Theresults showed that the accuracy of gravity field modeling forany types of radial basis function would be almost thesame, if the depths of SRBFs are chosen properly.